The importance of surgical staging in the treatment of malignant pleural mesothelioma

Our plain-English summary of The importance of surgical staging in the treatment of malignant pleural mesothelioma, by V.W. Rusch, E. Venkatraman (The Journal of Thoracic and Cardiovascular Surgery, 1996).

The study

• Authors: V.W. Rusch, E. Venkatraman
• Journal: The Journal of Thoracic and Cardiovascular Surgery
• Published: 1996;111(4):815-25; discussion 825-6
• Cited by: 152 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Progress in the therapy of malignant pleural mesothelioma is limited by the lack of an adequate staging system and controversy about prognostic factors. This surgical series was analyzed to determine whether a new TNM staging system proposed by the International Mesothelioma Interest Group and certain prognostic factors could stratify patients in future clinical trials.

Methods: Thoracotomy was performed if computed tomographic scans showed resectable tumor confined to one hemithorax. Pleurectomy/decortication was done if visceral pleural tumor was minimal, and extrapleural pneumonectomy was done for more locally advanced disease. Complete resection was defined as no gross residual tumor. Adjuvant therapy was given as required by serial clinical trials. Patients had computed tomographic scans every 3 months until death. Prognostic factors were examined by log-rank and Cox regression analyses.

Results: From October 1983 to July 1994, a total of 131 thoracotomies were performed, resulting in 101 resections, 72 of which were complete. Extrapleural pneumonectomy was done in 50 patients and pleurectomy/decortication in 51. The ratio of men to women was 108:23. Median age was 63 years (range 32 to 80 years). Operative mortality was five of 131 patients (3.8%), three of 50 in the group having extrapleural pneumonectomy (6%). Ninety-five of the 131 tumors were epithelial. Fifty-one of 89 patients (57%) having node dissections had diseased nodes, 45 (50%) N2. By univariate analysis, type of resection, T and N status, stage, histologic type, and adjuvant therapy, but no gender or age, significantly affected survival. Type of resection, stage, and histologic type were significant in a multivariate analysis. Local recurrence occurred mainly after pleurectomy/decortication, and distant metastases developed after extrapleural pneumonectomy.

Conclusions: (1) N2 nodal disease is more frequent than previously reported; (2) the prognostic importance of histologic type is confirmed; (3) both T and N status influence outcome, and the International Mesothelioma Interest Group staging system successfully identifies patients whose prognosis is poor; (4) despite more locally advanced disease in most patients with extrapleural pneumonectomy, that approach provided better local control than pleurectomy/decortication but failed to improve survival because of distant metastatic disease. Contrary to past practice, future clinical trials should stratify for histologic type, must control for TNM stage, and must consider the impact of type of surgical resection on the pattern of relapse.

In plain English

This study reviewed a prospective surgical registry of 131 consecutive patients with malignant pleural mesothelioma who had exploratory chest surgery, all by the same surgeon, from October 1983 to July 1994. The authors applied a new staging system from the International Mesothelioma Interest Group (IMIG) to test whether it sorted patients by outlook. Of the 131, 101 had tumor removed: 50 by extrapleural pneumonectomy and 51 by pleurectomy/decortication. The 30-day operative death rate was 3.8% (5 of 131). Of 89 patients whose lymph nodes were dissected, 51 had cancer in the nodes, 45 of them in the N2 group. In separate comparisons, earlier stage, no lymph node spread and epithelial tumor type were each linked with significantly longer survival. In a combined analysis, stage, tumor type and type of operation remained significant. After pleurectomy/decortication, the cancer most often first came back in the same-side pleura. After extrapleural pneumonectomy, a first relapse at a distant site was more frequent. The study recorded only the first site of relapse. The authors concluded that the IMIG system appeared to classify patients by prognosis. The study did not report patients' asbestos exposure.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Retrospective application of the IMIG TNM staging system to a prospective single-surgeon surgical registry (surgical case series with survival analysis)
• Who was studied: 131 consecutive patients with biopsy-proved malignant pleural mesothelioma (108 men, 23 women; median age 63 years, range 32 to 80) who underwent exploratory thoracotomy by the same surgeon, October 1983 to July 1994. The authors were affiliated with Memorial Sloan-Kettering Cancer Center, New York, but the article does not state where all the operations took place.
• Exposure: Asbestos exposure was not assessed or reported for these patients. The factors compared for survival were type of operation (extrapleural pneumonectomy or pleurectomy/decortication), IMIG T and N status and stage, tumor histologic type, adjuvant therapy, completeness of resection, age, sex and platelet count.
• Main results:
  • 101 of 131 patients had a resection, 72 of which were complete (71% of resections, 55% of all thoracotomies)
  • 30-day operative mortality was 3.8% (5 of 131 patients) overall and 6% (3 of 50) among patients having extrapleural pneumonectomy
  • Complications occurred in 33 of the 131 patients (25%)
  • Of 89 patients having mediastinal lymph node dissection, 51 (57%) had nodal metastases and 45 (50%) had N2 disease
  • In univariate analysis, pleurectomy/decortication patients survived longer than extrapleural pneumonectomy patients (median survival 18.3 vs 9.9 months; p = 0.0054)
  • Patients with T1/T2 tumors survived significantly longer than those with T3/T4 tumors (p = 0.0079)
  • Patients with N0 disease survived significantly longer than those with nodal metastases (median 18.3 vs 9.4 months; p = 0.0074)
  • Stages I and II combined had significantly better survival than stages III and IV combined (p = 0.0001); median survival was 35 months for stage I, 16 for stage II, 11.5 for stage III and 5.9 for stage IV
  • Epithelial tumors (95 of 131 patients) had significantly better survival than other histologic types (median 15.1 vs 6 months; p = 0.0002)
  • In univariate analysis, no significant survival difference was found between complete and incomplete resection, by age (less or greater than 50 or 60 years), or between men and women
  • In multivariate analysis, only tumor stage (p = 0.0063), histologic type (p = 0.0064) and type of operation (p = 0.022) remained significant
  • As a first site of relapse, the same-side pleura was most common after pleurectomy/decortication, while distant first relapse was more frequent after extrapleural pneumonectomy
• The authors' conclusion: The authors concluded that the IMIG staging system appeared to classify patients according to prognosis, that N2 nodal disease was more frequent than previously reported, and that future clinical trials should include careful TNM staging with the IMIG system and stratification by histologic type.
• Limitations the authors state:
  • The numbers of patients in the T and N subgroups were too small for definitive statistical results.
  • Variation in adjuvant treatment and small numbers in each treatment group prevented a meaningful comparison of adjuvant therapy types.
  • The effect of sex was hard to assess because there were few women in the series.
  • N1 nodes were not always examined by the pathologist, so the true frequency of N1 disease is unknown.
  • Only the first site of relapse was reliably recorded, not later sites.
  • The higher rate of distant relapse after extrapleural pneumonectomy could reflect disease stage and nodal spread rather than the operation itself.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Staging, Pleural Mesothelioma, TNM Staging, Mesothelioma, Clinical Trial, Thoracotomy, Hemithorax, Pleurectomy/Decortication (P/D).

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